Interactive Variable Pathlength Device

• US 20090027678A1
• Filed: 04/10/2008
• Published: 01/29/2009
• Est. Priority Date: 04/13/2007
• Status: Active Grant

• Current Assignee: C Technologies Inc. (Repligen Corporation)
• Original Assignee: C Technologies Inc. (Repligen Corporation)
• Inventors: Salerno, Mark C., Harriston, Craig, Shih, Tsung
• Granted Patent: US 7,808,641 B2
• Time in Patent Office: Days
• US Class Current: 356/440
• CPC Class Codes: G01N 2021/0346 Capillary cells; Microcells
• CPC Class Codes: G01N 21/00 Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light G01N3/00 - G01N19/00 take precedence
• CPC Class Codes: G01N 21/0303 Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment G01N21/031 - G01N21/15 take precedence
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/59 Transmissivity G01N21/25 takes precedence
• CPC Class Codes: G01N 2201/0612 Laser diodes
• CPC Class Codes: G01N 2201/0853 Movable fibre optical member, e.g. for scanning or selecting
• CPC Class Codes: G01N 2201/121 Correction signals

Abstract

This disclosure relates generally to a sampling device, and, more particularly, a sampling device that facilitates spectroscopic measurements with a variable path length and the necessary software controlled algorithms, and methods for using such a device.

Claims

1. A method of determining the concentration of a sample comprising:

(a) placing the sample in a vessel;

(b) placing a probe within sample;

(c) taking an absorbance reading;

(d) moving the probe relative to the vessel by a predetermined increment taking an absorbance reading at a predetermined wavelength;

(e) repeating step (d) one or more times;

(f) generating a regression line from the absorbance values such that a slope of the regression line is obtained; and

(g) determining the concentration of the sample by dividing the slope of the regression line by the extinction coefficient of the sample.

3. The method of claim 1 wherein the predetermine increment is the same for each iteration.

4. The method of claim 1 wherein the predetermined increment is from about 0.005 mm to about 50 mm.

5. The method of claim 1 wherein the predetermined increment is from about 0.0002 mm to about 10 mm.

9. The method of claim 1 wherein the regression line has an R² value of from around 0.99950 to about 0.99999.

11. The method of claim 1 wherein the regression line has an R² value of from around 0.99990 to about 0.99999.

2. A method of determining the concentration of a sample comprising:

(a) placing the sample in a vessel;

(b) moving a probe relative to the vessel such that the probe makes contact with the bottom of the vessel

(c) moving the probe relative to the vessel such that the probe moves from the bottom of the vessel through the sample by a predetermined increment such that a preselected path length through the solution is obtained;

(d) taking an absorbance reading at a predetermined wavelength,

(e) repeating steps (c) and (d) sequentially one or more times;

(f) generating a regression line from the absorbance and path length such that a slope of the regression line is obtained; and

(g) determining the concentration of the sample by dividing the slope of the regression line by the extinction coefficient of the sample.

6. The method of claim 2 wherein the predetermine increment is the same for each iteration.

7. The method of claim 2 wherein the predetermined increment is from about 0.005 mm to about 50 mm.

8. The method of claim 2 wherein the predetermined increment is from about 0.0002 mm to about 10 mm.

10. The method of claim 2 wherein the regression line has an R² value of from around 0.99950 to about 0.9999.

12. The method of claim 2 wherein the regression line has an R² value of from around 0.99990 to about 0.99999.

13. A method of determining the extinction coefficient of a sample at a wavelength where the extinction coefficient is not known comprising:

(a) placing the sample in a vessel;

(b) placing a probe within the sample;

(c) taking an absorbance reading at a first predetermined wavelength where the extinction coefficient is known and a second predetermined wavelength where the extinction coefficient is not known;

(d) repeating step (c) one or more times to determine the ratio of the absorbance to the path length at the first wavelength and the second wavelength;

(e) calculate the extinction coefficient at the second wavelength from the ratios of the absorbance to path length at both wavelengths and the extinction coefficient for the first wavelength.

14. An instrument for determine the concentration of a sample at multiple path lengths comprising:

(a) a light source operably linked to a probe

(b) a sample vessel that can contain the sample;

(c) a motor operably linked to the sample vessel such that the sample vessel can be moved relative to the probe to provide variable path lengths;

(d) a probe that can carry electromagnetic radiation that can be moved relative to the sample vessel by the motor;

(e) a universal sliding mechanism;

(f) a detector that can detect electromagnetic radiation disposed such that the detector is substantially perpendicular to the electromagnetic radiation emanating from the probe; and

(g) software for calculating the concentration of the sample based on the information provided by the detector at the predetermined path lengths.

15. The instrument of claim 14, wherein the universal sliding mechanism is passively locked.

16. The instrument of claim 14, wherein the universal sliding mechanism is actively locked by a user.

17. The instrument of claim 14, wherein the universal sliding mechanism is operably linked to the probe.

18. The instrument of claim 14, wherein the universal sliding mechanism is operably linked to the sample vessel.

19. The instrument of claim 14, wherein the path lengths are between about 0.2 μ

m to about 1.0 mm

20. The instrument of claim 14, wherein the path lengths are between about 0.2 μ

m to about 1.0 μ

m

21. The instrument of claim 14, wherein the motor is operably linked to the sample vessel though a sample vessel stage.

22. The instrument of claim 14, wherein the motor is computer controlled.

23. The instrument of claim 14, wherein the software can calculate the concentration based on deriving the slope of a line based on the ratio of path length to absorbance values.

24. The instrument of claim 23, wherein the slope of the line is derived while the values are being measured.